1. Field of the Invention
The present invention relates to high-speed transmission electrical connectors for connecting daughter cards to mother boards.
2. Description of the Prior Art
In computers and communications technologies, the speed of signal transmission, the frequency of transmitted signals, and the density of components mounted on substrate are been increased. Consequently, high-speed transmission connectors for connecting such substrate to units have a great number of terminal contacts.
In such connectors, it is necessary to shield the contact elements. U.S. Pat. No. 4,655,518 discloses a connector which includes a pair of ground plates provided between mating housings each having rows and columns of contact elements thereon. Each ground plate has an extended contact portion which is brought into contact with a board when the connector is attached to the board.
However, the above connector failed to provide a characteristic impedance match for the transmission line because (1) the distance between the contact elements and the ground plate is different for each contact element, (2) the ground plates have few effects on the contact elements in locations opposite to the ground plate, and (3) there are no shields between the contact elements, thus disturbing the signal waveforms.